Diverting solid waste from landfills is increasingly important due to limited availability of landfill space, rapidly increasing landfill cost, and environmental threats. The U.S. is the largest global producer of PET containers at nearly 70 percent of the supply [reference 1]. In the U.S., estimates indicate that annual production of PET containers will reach more than 2 million tons [reference 2]. The recycling rate for PET is about 25 percent [reference 3]. Production of the waste filler materials is about 500 million tons for rock quarry crusher fines, 10 million tons of lime sludge, and 100 million tons for coal-combustion by-products. Recycling has emerged as the most practical method to deal with these high-volume waste problems.
In addition, the U.S. has about 19,782 sewerage systems serving about 170 million people or about 75 percent of the population [reference 4]. As with much infrastructure in this country, this subterranean component has also deteriorated due to normal aging, sulfuric acid degradation, under design, poor initial design, and minimal maintenance. It is estimated that 800,000 miles of sanitary sewer line in the U.S. are in need of rehabilitation and that we are currently making repairs at the rate of 2 percent per year [reference 5]. Sixteen thousand miles of rehabilitation with an estimated 8 thousand miles of new construction create a need for improved pipe material.
An object of the invention is to provide a polymer mortar composite pipe material that has several beneficial material properties over conventional Portland cement concrete (PCC) pipe and vitrified extra strength clay tile including high structural capacity, excellent acid resistance, and low density. Equally important is the fact that the material components of the polymer mortar composite formulation consist of recycled plastic and waste filler materials (rock quarry crusher fines, lime sludge or various coal combustion by-products). By using recycled, post-consumer waste polyethylene terephthalate (PET) instead of virgin plastic, which is petroleum derived material; use of a significant volume of crude oil can be reduced.
Another object of the invention is to provide a plunger-cast manufacturing method and system than can increase recycling through production of polymer mortar composite pipe using the composite material mixtures described herein.
Still another benefit of the invention derives from production of the polymer mortar pipe to provide a strong, lightweight, and durable pipe product for which there is currently tremendous need.